Direct production process of high hardness titanium sponge



United States Patent T 3,359,093 DIRECT PRODUCTION PROCESS OF HIGH 1 HARDNESS TITANIUM SPONGE Kizashi Takahashi, Nishinomiya, and Kimiyoshi Ono,

Toyonaka, Japan, assignors to Osaka Titanium Company Limited, Amagasaki, Japan, a corporation of Japan No Drawing. Filed Sept. 24, 1964, Ser. No. 399,099 Claims priority, application Japan, Oct. 2, 1963, 38/53,247 1 Claim. (Cl. 75-845) This invention relates to the direct production of high hardness titanium sponge as a raw material for high strength titanium mill products.

For the purpose of giving higher strength to titanium mill products, high hardness titanium of 110 to 160 BHN has recently come to be demanded. To meet this demand many inventions have been made. For instance, Japanese Patent No. 407,452 refers to a process for producing high hardness titanium sponge by diffusing any required metallic element or its oxide at a high temperature in a vacuum or an inert gas. But complicated treatments and subsequent fabrications are required and the produced titanium sponge is costly. Moreover, it is diflicult to obtain the required homogeneity in the product. According to this invention, however, these faults are eliminated, and homogeneous and inexpensive titanium sponge of high hardness can be produced.

It is a well-known fact that hard titanium sponge can be produced when oxygen-dissolving titanium tetrachloride is reduced. Solubility of gaseous oxygen in titanium tetrachloride is discussed in Bureau of Mines, Report of Investigation 5665. It varies with the temperature of titanium tetrachloride and the solubility limit is about 30 p.p.m. at the most acceptable temperature. But this amount is too small to obtain a hardness of more than 160 BHN. An object of this invention is to dissolve more oxygen in titanium tetrachloride by employing water in place of gaseous oxygen. However, direct addition of water to titanium tetrachloride is not favorable because of the resultant high reaction heat and the generation of hydrogen chloride. And the volume of evaporated water can not be measured. In the present invention, titanic acid is used to give the reaction mixture exactly the desired amount of oxygen.

Titanic acid is prepared beforehand by mixing water with titanium tetrachloride at a temperature of less than 50 C. Then the titanic acid is added to the pure titanium tetrachloride to be reduced. Unfavorable reaction and evaporation of water are avoided. The hardness of the titanium sponge obtained by the conventional method and the present method is compared in Tables 1 to 4.

EXAMPLE I.-DIRECT ADDITION OF WATER TO TITANIUM TETRACHLORIDE 0.05, 0.15, 0.25, 0.35 and 0.45 kg. of water were added respectively to 1000 kg. of pure titanium tetrachloride at room temperature. In each case, a precipitate was formed along with the generation of heat and fumes resulting in a loss of a large amount of water. The precipitate where 0.05, 0.15 and 0.25 kg. of water was added dissolved easily within a short time. But when 0.35 kg. of water was added, the precipitate remained ten hours later. In the case of 0.45 kg. of water, the precipate did not dissolve so easily.

Hardness of titanium sponge produced from the above titanium tetrachloride Reducing the above treated oxygen-dissolving titanium tetrachloride, titanium sponge was produced by the Kroll process under several different conditions. Table 1 shows examples of hardness of the thus produced sponge.

3,359,093 Patented Dec. 19, 1967 TABLE 1 Added H 0 to Brinell hardness Test 1,000 kg. of TiCh N0. (kg) 0.1% Fe sponge 0.03% Fe sponge *Pui-e titanium tetrachloride was reduced. Several tests were conducted under the same condition.

Hardness in Table 1 varies widely. Thus this method is not suitable for practical use. However, this can be improved by adjusting exactly the oxygen content in titanium tetrachloride.

EXAMPLE II.INDIRECT ADDITION OF WATER TO TITANIUM TETRACHLORIDE Preparation 0 titanic acid At a temperature range between 0 C. and 30 C., 50 kg. of water was mixed with the same amount of pure titanium tetrachloride in a vessel cooled with ice. A yellow, viscous and transparent liquid resulted, which contained 14% titanium and 32% hydrogen chloride and had a specific gravity of 1.55. This treatment incurred neither fuming, heating nor loss of water.

Mixing titanic acid in titanium tetrachloride 0.1, 0.3, 0.5, 0.7 and 0.9 kg. of the above prepared titanic acid was mixed respectively with 1000 kg. of pure titanium tetrachloride at room temperature. When less than 0.7 kg. of titanic acid was added there was very little precipitation and it dissolved within five or six hours. When 0.9 kg. was added, the precipitate remained after twenty-four hours, though its amount was small. However, in general, the precipitate dissolved within a shorter time than that in the case of Example I. In this method, titanic acid could be mixed in titanium tetrachloride without loss of titanic acid and any adverse effects.

Hardness of titanium sponge produced from the above titanium tetrachloride The hardness of titanium sponge produced from thus prepared titanium tetrachloride is shown in Table 2.

TABLE 2 Added titanic acid Brinell hardness Test N o. to 1000 kgs. of

'IiCh (kg.)

0.1% Fe sponge 0.03% Fe sponge *Pure titanium tetrachloride was reduced. Several tests were conducted under the same condition.

The amounts of water in titanic acid are equal to those mentioned in the same test number of Table 1 and the dispersion is very small. These tests were conducted at about 20 C. or atmospheric temperature. But with lower temperatures, solubility of the precipitate will decrease. For instance, when the temperature of the mixed titanium tetrachloride was 0 C., the amount of precipitation increased and the hardness of titanium sponge became far lower as shown in Table 3.

be produced easily by changing the temperature of the TABLE 3 titanium tetrachlonde and correspondingly the amount Added titanic acid Brlnell hardness of tltamQ Test No. to lug) kgs. of What 1s claimed is:

(kg) 01% Fe sponge 003% Fe Sponge 5 A direct process for producing a high hardness titanium sponge useful as a raw material for high strength titanium mill products comprising the steps of E533 preparing titanic acid,

125430 112,113 adding said titanic acid to pure titanium tetrachloride 0.7 6-1 111-115 to rov'de a re ction mixture corn rii t an'um 0.9 126-130 110-116 P 1 a p sng 1t 1 tetrachloride and dissolved oxygen,

regulating the temperature of said reaction mixture, said temperature being increased to increase the oxygen content of said reaction mixture and decreased 5 ''to reduce the oxygen content of said reaction mixture, and reducing said reaction mixture to produce titanium sponge of controlled high hardness.

*Pure titanium tetrachloride was reduced. Several tests were conducted under the same condition.

Conversely, when the temperature of titanium tetra chloride is raised, a greater quantity of titanic acid can be mixed and titanium sponge of higher hardness, as shown in Table 4, can be obtained.

TABLE 4 References Cited iiifi f tif rfi 3ri.3?hofi? 8T6%%2%2Zi UNITED STATES PATENTS 2,948,608 8/1960 RCSIliCk 75-175.5 0 2 2,950,963 8/1960 SChOtt et a1. 75-84.5 20 (1):8 135 3,070,468 12/1962 Grant 75-175.5 X .s 174 S8 31 OTHER REFERENCES I Bureau of Mines Report of Investigations 5665; Methods for Improving Quality of Titanium Sponge Produced 0 by the Kroll Process; 1960.

DAVID L. RECK, Primary Examiner.

H. W. TARRING, Assistant Examiner.

1 Each hardness is the average of ten tests. 2 Pure titanium tetrachloride was reduced.

As shown, hardness increased more than twice, though the Fe content is the same as that of other experiments. Thus titanium sponge having any required hardness can 

